Pressure-limiting pump system for pressurizing a vessel

ABSTRACT

A pressure-limiting pump system for pressurizing a vessel, including a plunger terminating in a piston loose-fitting within a cylinder. The piston includes a flange forming the lip of an annular groove in the piston for supporting an O-ring seal. The groove is provided with a plurality of ports terminating in the piston within the cylinder. The O-ring is slidable on the piston groove surface. On the intake stroke, the O-ring moves to uncover the ports, and on the compression stroke, the O-ring moves to cover the ports to seal the compression chamber. When pressure exceeds a predetermined level, further compression causes air to bypass the O-ring and escape from the chamber, thereby limiting system pressure. The pump system may be mounted on-axis or off-axis in a tank sidearm. A handle is secured to the sprayer tank via shoulder inserts and is pivotable out of the way when filling the tank, yet can be locked in position as desired by a shift in pivot position.

RELATIONSHIP TO OTHER PATENTS AND APPLICATIONS

[0001] The present application claims priority of U.S. Provisional Patent Application Ser. No. 60/474,069, filed May 29, 2003.

TECHNICAL FIELD

[0002] The present invention relates to means for producing superatmospheric pressures in closed vessels; more particularly, to pump means for pressurizing a tank; and most particularly, to an improved piston pump sprayer system having internal relief means for preventing over-pressure of a sprayer tank.

BACKGROUND OF THE INVENTION

[0003] It is well known in the pumping art to pressurize a closed vessel or tank by using a compressor comprising a piston slidably sealed in a cylinder. Typically, the cylinder is isolated from the tank by a first check valve through which each successive compressive charge from the cylinder enters the tank. The piston is provided with second check valve, such as a variably-covered port through the piston, for drawing air into the cylinder during the intake stroke, and then for closing the port to permit compression of the air during the compression stroke.

[0004] Hand-pumpable sprayers are well-known in the art and are used for home spraying uses such as application of insecticides, fungicides, and fertilizers, as well as in commercial uses such as spraying concrete, curing compounds, and waterproofing. Typically, a pump system including a cylinder, piston, and check valves is disposed through a threaded cap or plug that fits onto or in a port in a sprayer tank, the cylinder extending into the tank after assembly. Generally, the port is also a fill port for adding materials to the tank between spraying operations.

[0005] In many prior art hand-pump sprayers, the sealant between the piston and the cylinder wall defining the second check valve is a skirt formed of a flexible material such as oiled leather and attached to the underside of the piston. The piston itself is loose-fitting in the cylinder. On the intake stroke of the piston, air is readily drawn into the cylinder past the piston and skirt; however, on the compression stroke, the skirt is expanded against the cylinder wall, sealing the annulus around the piston and permitting compression of the charge. In more recent hand-pump sprayers, the piston is sealed against the cylinder wall by a lubricated O-ring, and air is admitted to the cylinder as by a flapper check valve in the piston.

[0006] A problem with prior art hand-pump sprayers is that the piston becomes harder to pump as the tank pressure increases because greater pressure is required in the cylinder to open the first check valve against the accumulated pressure in the tank. This can present a serious problem for persons of limited strength, especially because a last full compression stroke is required to position the plunger for locking (the plunger handle also functions as the carrying handle for the sprayer). Further, it is possible for a strong operator, through persistent pumping, to raise the tank pressure above what is needed, and perhaps even above what is safe.

[0007] What is needed in the art of hand-pumping means for pressurizing vessels is a piston pump having a pressure-limiting bypass relief valve built in such that the pressure the pump can generate is predetermined by the construction of the bypass, thereby permitting relatively easy return of the plunger to its locking position and preventing over-pressuring of the vessel.

[0008] Another problem with prior art sprayers is that the hand-pump system is mounted axially of the sprayer tank through an opening in the tank cap, and the pump handle functions as a carrying handle when the tank cap is secured onto the tank. The pump plunger typically is provided with opposed radial tangs which pass through corresponding slots in the tank cap and are engaged to the underside thereof through a partial-revolution turn of the plunger. With extended use of the sprayer, the tangs can become worn and fail to reliably grip the tank cap, allowing a full sprayer to unexpectedly and undesirably drop down. Some sprayers tanks are provided with a shoulder strap, but a strap is designed for carrying use over a shoulder and makes a cumbersome carrying handle.

[0009] What is needed in the art of hand-pump sprayers is a separate carrying handle for the sprayer tank. What is further needed is an off-axis sidearm for accommodating the hand-pump system independently of the main tank loading port.

[0010] It is a principal object of the present invention to provide easier pumping of a hand-pumped pressure vessel, for example, a tank sprayer.

[0011] It is a further object of the present invention to automatically limit the pressure attainable in a pressure vessel being pressurized by a hand pump.

[0012] It is a still further object of the present invention to provide a means for carrying a hand-pumped pressure vessel independent of the hand-pump system.

SUMMARY OF THE INVENTION

[0013] Briefly described, a pressure-limiting hand pump system for pressurizing a vessel includes a pressure cylinder; a first check valve at an inner end of the cylinder for preventing back-flow of pressurized air or material from the vessel into the cylinder; and a plunger terminating in a piston within the cylinder and in a handle outside the vessel. The piston is loose-fitting within the cylinder and includes an annular flange which is also loose fitting, the flange forming the outer lip of an annular groove in the piston for receiving an O-ring which seals against both the piston and the cylinder wall. The groove has a longer axial extent than the diameter of the O-ring, and the portion of the groove adjacent the annular flange is provided with a plurality of ports connecting to passageways terminating in the piston face within the compression chamber. The O-ring is slidable on both the piston groove surface and the cylinder wall. On the intake stroke, the O-ring is moved axially of the piston in a first direction to uncover the ports, thus permitting air to fill the compression chamber. On the compression stroke, the O-ring is moved in the opposite direction to cover the ports and seal against the axial face of the flange, thereby sealing the compression chamber. The ports are so configured, however, that when the pressure in the compression chamber exceeds a predetermined level, further compression causes air to bypass the O-ring and escape from the chamber, thereby limiting the pressure of which the system is capable and allowing the plunger to be placed in the locking position without requiring excessive force in a last compressive stroke of the plunger.

[0014] In a first embodiment of a hand-pump sprayer in accordance with the invention, the hand-pump system is mounted substantially on-axis in the vessel cap for the main loading port of the sprayer tank. In a second and currently preferred embodiment, the hand-pump system is mounted off-axis in a tank sidearm defining a second opening in the vessel apart from the main loading port of the sprayer tank.

[0015] Each of the embodiments preferably includes a carrying handle pivotably mounted to the sprayer tank to facilitate carrying the entire sprayer without resort to using the pump handle. Preferably, the handle is secured to the sprayer tank via shoulder inserts that permit easy variations for storage mounting of various auxiliary components, such as a spray shield and different spray nozzles, without requiring redesign of the basic tank. Preferably, the handle is pivotable to be swung out of the way when filling the tank, yet can be locked in the upright position as desired by a simple shift in pivot position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0017]FIG. 1 is an exploded isometric view from the front of a first embodiment of a hand-pump pressure sprayer in accordance with the invention, having a hand-pump system disposed axially of the tank in a cap for a tank loading port;

[0018]FIG. 2 is an exploded isometric view from the front of a second embodiment of a hand-pump pressure sprayer in accordance with the invention, having a hand-pump system disposed in a sidearm of the sprayer tank;

[0019]FIG. 3 is an elevational view of the handle and plunger of the sprayer shown in FIG. 1;

[0020]FIG. 4 is an enlarged isometric view of the piston shown in FIG. 1;

[0021]FIGS. 5 and 6 are cross-sectional elevational views of the piston shown in FIG. 4, FIG. 5 showing the position of an O-ring during an intake stroke and FIG. 6 showing the position of an O-ring during a compression stroke;

[0022]FIG. 7 is an enlarged exploded isometric view of the hand-pump system shown in FIG. 2;

[0023]FIG. 8 is an isometric view from below of the piston end of the plunger shown in FIGS. 2 and 7;

[0024]FIG. 9 is a second isometric view of the sprayer shown in FIG. 2, showing use of the handle-mounting shoulder inserts for accommodating mounting of auxiliary components; and

[0025]FIG. 10 is an isometric view from above of the handle and shoulder inserts shown in FIGS. 2 and 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Referring to FIGS. 1, 3, and 4, a first embodiment 10 of a self-contained, hand-pumped utility sprayer includes a tank 12 defining a pressure vessel for holding materials to be sprayed, tank 12 having a swivel outlet 14 for attachment to a hose (not shown) for delivering the materials to a desired site. Tank 12 includes an axial port 16 at an upper end defined by a neck 18 having threads 20 formed on an outer surface thereof. The threads preferably are male threads as shown, although female threads on the inside of neck 18 are fully comprehended by the invention. A circular sealing element 22 is captured between the outer end of neck 18 and an annular surface (not visible in FIG. 1) within cap 24 in known fashion to prevent leakage of materials from port 16 when cap 24 is screwed onto neck 18.

[0027] Cap 24 is provided with a central opening (not visible in FIG. 1) for receiving a plunger 26 of a hand-pump pressurizing system 28. A tubular compression cylinder 30 is closed at its lower end 32 by a threaded cap 34 provided with an elastomeric check valve 36 as is known in the art and is sealed to cap 24 at its upper end 25. A first spring 38 is disposed within cylinder 30 for cushioning plunger subassembly 40 at the end of its downwards compression stroke. Subassembly 40 comprises plunger 26 assembled to piston 42 after insertion through cap 24 and retained therein by barbed bayonets 44. A second spring 46 is provided on plunger 26 for cushioning plunger subassembly 40 at the end of its upwards intake stroke. Cap 24 is preferably provided with a pressure relief valve assembly 48 for relieving residual pressure in tank 12 at the completion of a spraying operation. Plunger 26 is provided with a handle 50 for manually driving plunger subassembly 40 in cylinder 30.

[0028] Referring now to FIGS. 4, 5, and 6, piston 42 is formed preferably by injection molding of a suitably durable plastic polymer and comprises an upper chamber 52 and a lower chamber 54 separated by a septum 56. For convenience, septum 56 extends radially outwards to form a first radial flange 58. Piston 42 terminates at an upper end in a second flange 60 formed as a spring seat for spring 46 and surrounding an opening 62 for receiving bayonets 44. Upper chamber 52 is provided with one or more radial passages 64. Piston 42 terminates at a lower end in a third flange 66 formed as a spring seat for spring 38 and surrounding chamber 54. Lower chamber 54 is provided with one or more radial passages 68. Piston 42 is formed such that air may pass between flange 58 and the wall 70 of cylinder 30 during both the intake stroke (FIG. 5) and the compression stroke (FIG. 6).

[0029] Flanges 58,66 are spaced apart axially to form an annular channel 72 therebetween for receiving an O-ring 74 (shown in FIGS. 5 and 6; omitted from FIG. 4) for forming a sliding seal between wall 70 and piston 42. The axial extent of channel 72 is greater than the material diameter of O-ring 74. Thus, the O-ring in the channel acts as a second check valve for pump system 28. When piston 42 is raised within cylinder 30 as in the intake stroke, as shown in FIG. 5, O-ring 74 is urged away from flange 58 by friction with wall 70, allowing air to enter cylinder 30 by bypassing piston 42 via the periphery of flange 58 and passages 68. When piston 42 is lowered within cylinder 30 as in the compression stroke, as shown in FIG. 6, O-ring 74 is urged into contact with flange 58, thus sealing flange 58 against wall 70.

[0030] In accordance with the invention, O-ring 74 and channel 72 may be sized without undue experimentation to provide a relationship therebetween wherein air being compressed by piston 42 within cylinder 30 is able to escape by forcing O-ring 74 away from wall 70 and/or flange 58. For example, use of a 0.025 inch diametric interference between the o-ring 74 and the wall 70 would work well. Thus, the piston can be configured to provide pressure relief means at a predetermined pressure, as desired, within cylinder 30. In an alternate embodiment one or move radial grooves 61 may be scribed in axial face 59 of flange 58 to permit a controlled amount air to escape past O-ring 74 when air is being compressed by piston 42 to provide pressure relief means at a predetermined pressure.

[0031] Referring to FIGS. 2, 7, and 8, a second embodiment 10′ of a self-contained, hand-pumped utility sprayer includes a tank 12′ defining a pressure vessel for holding materials to be sprayed, tank 12′ having a swivel outlet 14′ for attachment to a hose (not shown) for delivering the materials to a desired site. Tank 12′ includes an axial port 16′ on an upper end defined by a neck 18′ having threads 20′ formed on an outer surface thereof. The threads preferably are male threads as shown, although female threads on the inside of neck 18′ are fully comprehended by the invention. A circular sealing element 22′ is captured between the outer end of neck 18′ and an annular surface (not visible in FIG. 1) within cap 24′ in known fashion to prevent leakage of materials from port 16′ when cap 24′ is screwed onto neck 18′.

[0032] Cap 24′ is provided with a central opening 27 for receiving a pressure relief valve assembly 48 for relieving residual pressure in tank 12′ at the completion of a spraying operation.

[0033] Tank 12′ includes a sidearm 80 having a threaded port 82 for receiving a hand-pump pressurizing system 28′. Sidearm 80 and port 82 define a second port in tank 12′ additional to first port 16′. Thus port 16′ may function as a materials loading port without requiring that hand-pump pressurizing system 28′ be disassembled from tank 12′ as in the prior art wherein the pressurizing system is disposed axially through the main loading port cap, as in embodiment 10. A tubular compression cylinder 30′ is closed at its lower end 32′ by a threaded cap 34′ provided with an elastomeric check valve 36′ as is known in the art. A first spring (not visible in FIG. 2) may be disposed within cylinder 30′ for cushioning plunger subassembly 40′ at the end of its downwards compression stroke. Subassembly 40′ comprises a plunger 26′ integral with a piston 42′ formed preferably by injection molding of a suitably durable plastic polymer. Plunger 26′ is provided with a handle 50′ for manually driving plunger subassembly 40′ in cylinder 30′.

[0034] Piston 42′ (FIG. 8) comprises a first radial flange 58′ and a second radial flange 66′ provided with one or more passages 68′. Piston 42′ is formed such that air may pass between flange 58′ and the wall of cylinder 30′ during both the intake stroke and the compression stroke. Flanges 58′,66′ are spaced apart axially to form an annular channel 72′ therebetween for receiving an O-ring 74′ (shown in FIGS. 2 and 7; omitted from FIG. 8) for forming a sliding seal between the wall of cylinder 30′ and piston 42′. The axial extent of channel 72′ is greater than the material diameter of O-ring 74′. Thus, the O-ring in the channel acts as a second check valve for pump system 28′. When piston 42′ is raised within cylinder 30′ as in the intake stroke, O-ring 74′ is urged away from flange 58′ by friction with the cylinder wall, allowing air to enter cylinder 30′ by bypassing piston 42′ via the periphery of flange 58′ and passages 68′. When piston 42′ is lowered within cylinder 30′ as in the compression stroke, O-ring 74′ is urged into contact with flange 58′, thus sealing flange 58′ against the cylinder wall.

[0035] In accordance with the invention, O-ring 74′ and channel 72′ may be sized without undue experimentation to provide a relationship therebetween wherein air being compressed by piston 42′ within cylinder 30′ is able to escape by forcing O-ring 74′ away from the wall of cylinder 30′ and/or flange 58′. Thus, the piston can be configured to provide pressure relief means at a predetermined pressure, as desired, within cylinder 30′. Alternatively, as shown in FIG. 8, one or move radial grooves 61′ may be scribed in axial face 59′ of flange 58′ to permit a controlled amount air to escape past O-ring 74′ when air is being compressed by piston 42′ to provide pressure relief means at a predetermined pressure.

[0036] Pressurizing system 28′ further comprises a guide element 84, having an anti-rotation snap tab 86 for engaging with a detent 88 in the outer end of cylinder 30′. Cylinder 30′ includes a shoulder 90 for sealingly engaging threaded neck 92 of sidearm 80. A threaded closure ring 94 secures system 28′ to neck 92. Preferably, system 28′ further includes a stirrup ring 96 which may snap onto closure ring 94. Ring 96 includes one or more open stirrups 98,100, which may be of different sizes, for use as storage sites for the sprayer's hose and/or wand apparatus (not shown).

[0037] Referring to FIGS. 2, 9, and 10, sprayer embodiment 10′ may be further provided with a rotatable handle system 102 comprising first and second shoulder inserts 104 a,104 b which may or may not be mirror images of one another. Tank 12′ includes recesses 106 a,106 b for receiving the shoulder inserts. Inserts 104 a,104 b are secured into recesses 106 a,106 b by any suitable securing means, and preferably are releasably secured by one or more bishop snaps 108 formed in the inserts and insertable into blind bores 110 formed in tank 12′. A reason for providing shoulder inserts rather than engaging handle 112 directly into tank 12′ is that the configuration of the inserts may be readily adapted to provide special features 113 for removable storage of various auxiliary attachments and components, such as a spray shield 114, alternative nozzles (not shown), etc. as may be provided with various models of sprayer, without requiring expensive alteration to the mold for the common tank 12′.

[0038] Handle system 102 preferably is configured to permit more than one handle position and function. Handle 112 is provided with opposed bishop-type studs 116, each including a split flange 118. Shoulder inserts 104 a,104 b each include an opening 120 that is elongate in the axial direction of tank 12′. Studs 116, when inserted into openings 120, are pivotably retained therein by flanges 118, allowing handle 112 to extend upwards as shown in FIG. 2 for carrying of sprayer 10′ or to be folded to one side (not shown) for access to cap 24′ and port 16′.

[0039] Further, each shoulder insert is provided with a flush-mounted saddle element 122 comprising a short extension 124, a long extension 126 extending generally in the axial direction of tank 12′, and a saddle portion 128 in between. Handle 112 is provided with opposed inwardly-extending tangs 130 positioned on handle 112 such that when studs 116 are urged to an upward extreme in openings 120 the tangs can pass short extensions 124 but cannot pass long extensions 126.

[0040] These relationships confer the following benefits:

[0041] a) when the handle is released after being used to carry sprayer 10′, tangs 130 come to rest on saddle portions 128 between extensions 124,126; thus the handle is maintained in an upright position by extensions 124,126, to be easily re-grasped by a user;

[0042] b) when the handle is raised such that tangs 130 can clear short extensions 124, the handle then may be pivoted past pump assembly 28′ to permit access to cap 24′ and port 16′ and to maintain access to, and servicing of, pump assembly 28′; and

[0043] c) when the handle is re-grasped in the upright position, long extensions 126 and tangs 130 prevent handle 112 from swinging past an upright position, thus preventing tank 12′ from undesirably swinging against the legs of a user while the sprayer 10′ is being carried.

[0044] While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims. 

What is claimed is:
 1. A pressurizing system for pressurizing a vessel, comprising: a) a cylinder in communication with the interior of said vessel; b) a first check valve disposed in said cylinder and defining an interface between said cylinder and said vessel interior for preventing blowback of pressure from said vessel into said cylinder; c) a piston disposed for reciprocation within said cylinder to define a compression chamber therein, said piston including an annular channel and including ports communicating between said channel and said compression chamber; and d) an O-ring slidably disposed in said channel, whereby said ports are covered by said O-ring during a compression stroke of said piston and are uncovered by said O-ring during an intake stroke of said piston, said O-ring being sealably mating with a wall of said channel and a wall of said cylinder during said compression stroke, said channel wall and said O-ring being sized such that air being compressed within said cylinder may escape therefrom between said wall and said O-ring when pressure within said cylinder reaches a predetermined level.
 2. A pressurizing system in accordance with claim 1 further comprising a plunger attached to said piston for actuating said piston.
 3. A pressurizing system in accordance with claim 2 further comprising a handle attached to said plunger.
 4. A system for compressing air and storing compressed air, comprising: a) a pressure vessel having a port; and b) a pressurizing system disposed in said port, said pressurizing system including a cylinder in communication with the interior of said vessel, a first check valve being disposed in said cylinder and defining an interface between said cylinder and said vessel interior for preventing blowback of pressure from said vessel into said cylinder, a piston being disposed for reciprocation within said cylinder to define a compression chamber therein, said piston including an annular channel and including ports communicating between said channel and said compression chamber, and an O-ring being slidably disposed in said channel, wherein said ports are covered by said O-ring during a compression stroke of said piston and are uncovered by said O-ring during an intake stroke of said piston, said O-ring sealably mating with a wall of said channel and a wall of said cylinder during said compression stroke, said channel wall and said O-ring being sized such that air being compressed within said cylinder may escape therefrom between said wall and said O-ring when pressure within said cylinder reaches a predetermined level.
 5. A system in accordance with claim 4 wherein said system is a pressure sprayer.
 6. A system in accordance with claim 4 wherein said pressurizing system is a hand-pump system.
 7. A system in accordance with claim 4 wherein said vessel includes a single entrance port and wherein said pressurizing system is disposed through a cap for covering said port.
 8. A system in accordance with claim 7 wherein said port, said cap, and said pressurizing system are disposed axially of said vessel.
 9. A system in accordance with claim 4 wherein said vessel includes first and second ports, said second port being disposed in a non-axial sidearm, and wherein said pressurizing system is disposed in said second port.
 10. A system in accordance with claim 5 wherein said pressurizing system includes means for storage of a sprayer wand.
 11. A system in accordance with claim 10 wherein said means includes a ring assembled to said pressurizing system and having at least one stirrup projecting therefrom.
 12. A system in accordance with claim 4 further comprising handle means for carrying said system, said handle means comprising: a) first and second shoulder inserts removably attachable to said pressure vessel, said shoulder inserts being provided with elongate openings; and b) a generally U-shaped handle including means for pivotably retaining said handle in said elongate openings.
 13. A system in accordance with claim 12 further comprising first and second recesses formed in said vessel for receiving said first and second shoulder inserts.
 14. A system in accordance with claim 12 wherein at least one of said shoulder inserts is provided with a saddle element including a short extension, a long extension, and a saddle portion therebetween, and wherein said handle is provided with at least one tang for variably engaging said saddle element to position said handle.
 15. A pressurized sprayer system, comprising: a) a pressure tank for holding materials to be sprayed; b) first and second shoulder inserts removably attachable to said pressure tank, said shoulder inserts being provided with elongate openings; and c) a generally U-shaped handle including means for pivotably retaining said handle in said elongate openings.
 16. A sprayer system in accordance with claim 15 further comprising first and second recesses formed in said tank for receiving said first and second shoulder inserts.
 17. A sprayer system in accordance with claim 16 wherein at least one of said shoulder inserts is provided with a saddle element including a short extension, a long extension, and a saddle portion therebetween, and wherein said handle is provided with at least one tang for variably engaging said saddle element to position said handle.
 18. A pressurizing system for pressurizing a vessel, comprising: a) a cylinder in communication with the interior of said vessel; b) a first check valve disposed in said cylinder and defining an interface between said cylinder and said vessel interior for preventing blowback of pressure from said vessel into said cylinder; c) a piston disposed for reciprocation within said cylinder to define a compression chamber therein, said piston including an annular channel and including ports communicating between said channel and said compression chamber; and d) an O-ring slidably disposed in said channel, whereby said ports are covered by said O-ring during a compression stroke of said piston and are uncovered by said O-ring during an intake stroke of said piston, e) at least one groove disposed in a flange of said piston, said groove being sized such that air being compressed within said cylinder may escape therethrough during a compression stroke of said piston. 